Laser removal of conductive seed layers

ABSTRACT

Various techniques are disclosed for an apparatus and a method to remove a layer from a substrate having a pattern formed on the layer. In one example, the apparatus comprises a stage configured to receive and hold the substrate. The apparatus may further comprise an irradiating device comprising a projection lens and configured to irradiate the surface of the substrate with pulses of laser light having a selected fluence to remove an interstitial portion of the layer between the pattern without removing the pattern for corresponding irradiated areas of the substrate. The pulses of laser light may be focused through the projection lens, and the stage and the projection lens may be configured to move continuously relative each other to irradiate a plurality of areas of the substrate with the pulses of laser light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/348,063 filed Jan. 11, 2012 and entitled “LASER REMOVAL OF CONDUCTIVESEED LAYERS” which is incorporated herein by reference in its entirety.

U.S. patent application Ser. No. 13/348,063 filed Jan. 11, 2012 claimsthe benefit of and priority to U.S. Provisional Patent Application No.61/432,539, filed Jan. 13, 2011, and entitled “LASER REMOVAL OFCONDUCTIVE SEED LAYERS” which is incorporated herein by reference in itsentirety.

BACKGROUND

1. Technical Field

This application relates to techniques for fabricating electronicssubstrates and semiconductor wafers in general, and more particularly,to systems and methods for removing surplus conductive seed layers fromsuch substrates and wafers using lasers.

2. Related Art

In the Advanced Electronics Packaging and Electronics Substrateprocessing fields, a so-called “seed layer” of copper (Cu), titanium(Ti), titanium/copper (Ti/Cu), titanium tungsten/copper (TiW/Cu),titanium (Ti), chrome/copper (CrCu), nickel (Ni), palladium (Pd) or thelike, is deposited, typically by sputtering or other equivalent methods,onto a wafer or substrate, and then used as a target for platingelectrically conductive traces or structures thereon, e.g., bondingpads, redistribution layers (RDLs) and the like. Once the desiredconductive traces are formed and the photoresist used for patterningremoved, the surplus seed layer, i.e., the seed layer still present onthe substrate outside of the conductive traces and structures, must beremoved, which is conventionally effected using a wet chemical, drychemical or a plasma etch process.

However, there are a number of drawbacks associated with theseconventional surplus seed layer removal processes. For example, they canprevent the formation of finer pitch structures, they also etch theconductive circuitry that is meant to be left behind, they promoteundercutting and thus, yield of the metalized features left behind,leave contaminates on the seed layer that can mask the etch affectingyield, they necessitate increased process times and more expensivemethodologies and equipment and thereby constitute an undesirably highercost of ownership, limited process capability and are less friendly tothe environment.

Accordingly, there is a need in this industry for systems and methodsfor the removal of surplus seed layers that enable higher yields, theproduction of finer pitch structures and that are simpler, lessexpensive, and more friendly to the environment than the chemical, dryor plasma etch processes of the prior art.

SUMMARY

In accordance with one or more embodiments of the present invention,systems and methods are provided for removing surplus seed layers fromsubstrates using laser ablation systems that avoid the above and otherdrawbacks of the prior art.

In one example embodiment, an apparatus for removing a surplus seedlayer from a surface of a substrate comprises a stage configured toreceive and hold the substrate and a device for irradiating the surfacewith laser light (e.g., a fluence of laser light) effective to ablatethe surplus seed layer from the surface.

In another embodiment, a method for removing surplus seed layer from thesurface of a substrate comprises irradiating the surface with laserlight (a fluence of laser light) effective to ablate the surplus seedlayer away from the surface.

In another embodiment, a method for making conductive traces on asurface of a substrate comprises forming a dielectric layer on thesurface of the substrate, forming a seed layer of an electricallyconductive material on the dielectric layer, forming a layer ofphotoresist on the seed layer, patterning the photoresist, forming theconductive traces on the patterned photoresist and seed layer, removingthe photoresist from the substrate, and irradiating the surface of thesubstrate with laser light (a fluence of laser light) effective toablate the seed layer from areas of the substrate surface exclusive ofthe conductive traces.

A better understanding of the above and other features and advantages ofthe systems and methods of the present invention can be had from aconsideration of the detailed description of some example embodimentsthereof below, particularly if such consideration is made in conjunctionwith the appended drawings, wherein like reference numerals are used toidentify like elements illustrated in one or more of the figuresthereof.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS

FIG. 1 is a schematic side elevation view of an example embodiment of anapparatus for removing a surplus seed layer from a substrate inaccordance with an embodiment of the present invention;

FIG. 2 is a schematic side elevation view of an example embodiment of adebris removal system for collecting and storing the surplus seed layerremoved by the apparatus of FIG. 1;

FIG. 3 is a partial top plan view of a semiconductor wafer having asurface upon which a plurality of identical conductive patterns havebeen formed, showing the wafer before the surplus seed layer is removedtherefrom in accordance with an embodiment of the present invention;

FIGS. 4A-4D are schematic partial side elevation views of a substrateshowing sequential steps involved in an example method for the removalof a surplus seed layer therefrom in accordance with an embodiment ofthe present invention;

FIGS. 5A and 5B are schematic top plan views of a wafer, showingalternative methods for sweeping a laser beam relative to a surface ofthe wafer from which a surplus seed layer is being removed in accordancewith an embodiment of the present invention;

FIGS. 6A and 6B are photomicrographs of portions of a substrate fromwhich a surplus seed layer has been removed in accordance with anembodiment of the present invention, respectively taken at differentmagnifications; and,

FIGS. 7A and 7B are process flow diagrams respectively showingsequential steps involved in the formation of conductive tracestructures on a surface of a substrate and the subsequent removal of asurplus seed layer therefrom in accordance with an embodiment of thepresent invention.

DETAILED DESCRIPTION

In the electrical substrate and wafer fabrication industry, theformation of conductive structures, e.g., traces, bonding pads,conductive bump interconnects, redistribution layer (RDL) traces, andthe like, upon a surface of the substrate typically begins with theformation of a dielectric or electrically insulating layer on a“working” or “active” surface of the substrate. The insulating layer cancomprise a polymer, such as a polyimide, or polybenzobisoxazole or“PBO,” e.g., HD8930, HD8820 or HD4100, all available from HDMicroSystems (http://hdmicrosystems.com), which can be deposited ontothe substrate, for example, by a spinning operation. Alternatively,another type of insulator, such as silicon dioxide (SiO₂) or siliconnitride (SiNx), can be formed on the substrate, such as a silicon wafer,using well-known oxidization techniques.

Following this, a “seed layer” of, e.g., Cu, Ti/Cu, TiW/Cu, Ti, CrCu,Ni, Pd or the like, is deposited over the insulating layer on thesubstrate, e.g., by sputtering. For example, a Ti/Cu seed layer having athickness of, e.g., less than about 700 nanometers (nm) can be formedover the insulating layer. A photoresist is then applied on top of themetal seed layer, where it is patterned and developed using well-knownphotolithographic techniques. Following the resist develop process, thepatterned metal seed layer provides a target for depositing a conductivematerial, e.g., Cu, onto the Ti/Cu seed layer exposed within thepatterned photoresist, for example, using conventional platingtechniques.

Following this, the resist is stripped from the substrate, leaving thedesired patterned, thicker Cu structures, e.g., circuit traces, pads,conductive bump interconnects, RDL traces, and the like, along with thethinner, “surplus” Ti/Cu seed layer remaining between the structuredpatterns, such as exhibited on the plated wafer 300 illustrated in FIG.3 (e.g., although a round wafer is shown as an example, the shape, suchas round or square or other desired shape, and dimensions are notlimiting). As can be seen in FIG. 3, the wafer 300 includes a pluralityof identical, thicker Cu structures 302, as well as a thin, surplus seedlayer 304 located interstitially of the Cu structures 302, which must beremoved to prevent short circuiting between the structures 302.

Conventionally, surplus seed layers are removed from wafers orsubstrates using either a wet, dry or plasma etch process. However,there are a number of drawbacks associated with these conventionalprocesses, in that they become “process-limited” as the requirement forfiner pitch structures and yields are required, and the process timesand methods involved can constitute a higher cost of ownership inapplications in which this consideration is highly sensitive.Additionally, some of the conventional processes are environmentallyunfriendly.

For example, in the case of the wet etching process, wet etching causesan undercutting of the metal circuitry desirably left behind, e.g., theCu “pillars” or RDL traces 302 formed on the substrate 300. Thisundercutting reduces the contact area of the metal circuitry, therebycontributing to lower yields and product reliability.

Additionally, the wet etch process is not selective. Thus, all metalfeatures are etched, including those the manufacturer wishes to leaveremaining, e.g., metal circuitry traces and interconnect bumps. Asinterconnect bumps and circuitry traces become smaller by design, theeffectiveness of wet etching becomes increasingly limited, because thesame amount of etching occurs on the circuitry patterns which themanufacturer wants to leave behind as occurs on the unwanted surplusseed layer. This adversely affects product reliability and limitsfeature dimensions, e.g., the pitch, of the circuitry being left behind.As will be appreciated, when the pitch between relativelyhigh-aspect-ratio features decreases, this also increases the difficultyin removing the seed layer by means of the wet etch process. This, inturn, provides constraints on chip design and limits the spacing thatcan be used between the metal structures.

Additionally, as will be appreciated, the wet etch process uses harshchemicals that etch away the metal seed layer. However, the processsteps prior to the etching step involve applying various materials tothe metal seed layer, residual amounts of which can be left behind asresidues. These residues, which can be several nanometers thick, act ascontaminates on the metal seed layer that “mask” the wet etch process,causing incomplete removal of the metal seed layer and resulting inshorts.

Further, the wet etch process requires relatively large amounts ofcaustic chemicals to etch away the metal seed layer. In addition, thesesame etch chemicals also tend to leach into the underlying insulatingmaterial, with a resultant negative yield affect. The by-product of thechemical etch process is a hazardous waste that requires costlyhazardous waste disposal methods. The precious metals that are removedare saturated into the chemical etchant and are disposed of along withthe chemical etchant. With the worldwide concentration on so-called“Green” initiatives, use and disposal of these chemicals are deemedhighly undesirable.

The plasma etching process entails similar drawbacks, to which are addedthe higher costs typically associated with the equipment needed toproduce and control the plasma etch.

However, the systems and methods described herein for removing surplusseed layers from substrates using lasers effectively overcome the aboveand other drawbacks of the conventional methods and offer enhancedprocess capabilities and lower manufacturing costs. They enableproduction of devices at lower costs and larger volumes by using asimple, clean laser ablation technique. As discussed further herein,laser-based seed layer removal can thus reduce the overall productmanufacturing costs and improve process capability and yields.

Additionally, laser removal of the surplus seed layer causes noundercutting of the metal circuitry, thereby enabling better reliabilityas circuitry features become smaller. The laser processing method isalso more selective in its material removal, in that it removes theundesired surplus seed layer without removing the desired thickercircuitry patterns (e.g., metal bumps and RDL traces). The constraintson chip design and limits on the spacing that can be used between themetal structures are eliminated using the laser process. Additionally,with the laser removal process, processing contaminates have no affecton the ablation process, thus eliminating the yield issues that affectthe wet or dry etch processes. Moreover, the laser process requires noharsh chemicals to etch the substrate, thereby contributing to the Greeninitiatives. Further, as described in more detail below, a majority ofthe precious metals in the surplus seed layer can be reclaimed throughthe ablation process, thereby enabling the manufacturer to recycle andreuse the metal that is removed.

Apparatus useful for carrying out the surplus seed layer laser ablationtechniques described herein are illustrated in FIGS. 1 and 2, whereinFIG. 1 is a schematic side elevation view of an example embodiment of anapparatus 100 for laser removal of a surplus seed layer from asubstrate, and FIG. 2 is a schematic side elevation view of an exampleembodiment of a debris removal system 200 for collecting and storing thesurplus seed layer removed by the apparatus 100 of FIG. 1, as discussedherein.

As can be seen with reference to FIG. 1, the example laser ablationapparatus 100 comprises a movable X-Y translation stage 102 upon which asubstrate 104 is retained for laser processing, an irradiating devicecomprising a laser light source 106 operable to produce a beam 108 ofcoherent laser light having a specific, predetermined wavelength, and aplurality of optical elements operable in cooperation with each other toselectably irradiate the upper surface of the substrate 104 with thelaser light beam 108 and to control the fluence of the light beam atthat surface. In the particular example embodiment illustrated in FIG.1, these elements include a plurality of turning mirrors 110 arranged toalter the direction of the light beam 108, a shutter 112 operable toselectably block or allow passage of the light beam, an attenuator 114operable to selectably attenuate the light beam, an anamorphic tunnel116 operable to control the shape of the light beam, a homogenizer 118operable to control the uniformity of the light beam, an anamorphiccondenser lens 120 operable to selectably shape and focus the lightbeam, a mask 122 configured to crop the light beam, and a projectionlens 124 operable to condense and focus the light beam on the uppersurface of the substrate 104.

As those of skill in the art should appreciate, the particularembodiment of laser ablation apparatus 100 illustrated in FIG. 1 ispresented by way of example only, and not by way of any limitation, andaccordingly, other devices having a fewer or greater number and/or typesof laser light sources and/or optical elements can be confected thatmight also be effective in the removal of surplus seed layers, dependingon the particular application at hand.

As will be further appreciated, many types of laser light sources 106can be used for effective ablation of seed layers, including withoutlimitation, solid state, LED and gas lasers. For example, an excimerlaser of the type available from, e.g., Tamarack Scientific Co., Inc.(http://www.tamsci.com) can be used advantageously. An excimer laseruses a combination of a noble gas (e.g., argon, krypton, or xenon) and areactive gas (fluorine or chlorine) which, under the appropriateconditions of electrical stimulation, create a pseudo-molecule called an“excimer” (or in the case of noble gas halides, an “exciplex”) which canonly exist in an energized state, and which give rise to laser lightwith a wavelength in the ultraviolet region.

The UV light from an excimer laser is absorbed efficiently by bothbiological matter and organic compounds. Rather than burning or cuttingthe material irradiated therewith, the excimer laser adds enough energyto disrupt the molecular bonds of the surface tissue, which effectivelydisintegrates into the air in a tightly controlled manner throughablation rather than through burning. Thus, excimer lasers have theuseful property that they can remove exceptionally fine layers ofsurface material with almost no heating or change to the remainder ofthe material, which is left virtually unaffected.

FIG. 2 illustrates an example embodiment of a debris removal system 200for collecting and storing the material of the surplus seed layerremoved by the example laser ablation apparatus 100 of FIG. 1. As can beseen in FIG. 2, the debris removal system 200 is disposed closely belowand adjacent to the projection lens 124 of the ablation apparatus 100and comprises a frusto-conical chamber 202 with an open top and bottom,around the periphery of which is disposed a plurality of orifices orjets 204 for jetting streams of a gas, e.g., air, onto the upper orworking surface 206 of a substrate 104 from which a seed layer is beingablated. As indicated by the arrow 210, the gas jets 204 work incooperation with an exhaust/pump 208 to create a high velocitycross-flow of the gas in the chamber 202 that sweeps away the loose,ablated-away seed layer from the substrate surface 206 and collects itfor recycling and reuse, as discussed above, in the manner of a smallbut powerful vacuum cleaner.

As discussed in more detail below, the debris removal system 200 isfixed below the projected laser beam between the projection lens 124 andthe substrate 104, and moves conjointly with the laser ablationapparatus 100 relative to the substrate 102, or vice-versa, such that itcleans the same area as that being irradiated by the laser apparatus100. As will be appreciated, this movement of the laser ablationapparatus 100 relative to the substrate 102 can be effected by movingthe substrate 104 relative to the apparatus 100 (using, e.g., the X-Ytranslation stage 102), by moving the apparatus 100 relative to thesubstrate 104, or by moving both of the two devices relative to eachother.

The laser removal of thin conductive seed layers of materials, such ascopper, gold, silver, titanium, palladium, tantalum and many others, canbe directly ablated away when applied to an underlying dielectric orpolymer using an Excimer laser process. Laser ablation is a“subtractive” process in which the thin metal layer is ablated awaydirectly by a high-energy UV beam projected from the Excimer or otherlaser apparatus 100. Typically, the metal seed layer is formed with athickness of less than about 1 micrometer (μm) in order for the ablationprocess to occur. At this thickness, the metal seed layer readilyablates. All other circuit structures present on the substrate, i.e.,those having a thickness greater than about 1 μm, require asignificantly higher amount of laser fluence to remove. Thus, thedesired circuit patterns remain, while the seed layer is readilyremoved. The result is a complete removal of the metal seed layerwithout damaging the underlying polymer layer or any ablation of the RDLtraces, pillars or other circuitry patterns that it is desired to leaveon the substrate 104.

As illustrated in FIGS. 4A-4D, during the ablation process, the metal(Ti/Cu in the figures) seed layer 402 disposed on the dielectric orpolymer layer 404 on the substrate 104 (Si/dielectric in the figures)fractures in the area 406, between the thicker circuitry pillars ortraces 410, irradiated by the laser beam 108 by the strong tensilestress induced by a rapid heating and cooling cycle resulting from thebeam 108 of laser light incident thereon, causing it to separate fromthe underlying dielectric or polymer layer 404. The laser beam pulse 108is only partially absorbed by the underlying dielectric or polymer layer404 so that only a small part of the energy of the beam 108 reaches themetal-substrate interface. The discontinuity at the interface thusproduces a high electric field gradient, which cause the thin metal seedlayer 402 to be ejected from the surface of the substrate 104 at a highspeed. The ablated metal layer 408 (e.g., as shown in FIG. 4D) that isejected from the substrate 104 is similar to a fine powder, which canthen be reclaimed using the debris collection system 200 described abovein connection with FIG. 2 as it is being ablated. Since the metal seedlayer 402 in the area 406 is “shocked” from the surface of the substrate104 and not directly cut or burned away, the underlying dielectric orpolymer material 404 is not damaged during the process.

The amount of laser energy required to remove the seed layer 402 isquite low, and thus, it is possible to remove large areas of seed metalat a time, offering attractive throughput in comparison to theconventional alternatives of the wet, dry or plasma etch processes. Asillustrated in FIG. 5A, a serpentine scan, indicated by the alternatingtransverse arrows, of a small square or rectangular laser beam area 502can be sequentially stepped and repeated over the entire surface of thesubstrate 102 to ablate away the seed layer 402. Alternatively, asindicated by the single transverse arrow in FIG. 5B, this can also beeffected in a stepped, single-pass scan across the substrate 104 of arelatively narrow laser beam area 504 that is longer than the substrate104. In either embodiment, while scanning/stepping across the substrate104, the laser apparatus 100 is operated in a pulsed fashion, causingthe seed layer 402 in the area 502 or 504 currently being illuminated bythe laser beam 108 to be ablated away without damaging the underlyingmaterials or the adjacent, thicker metalized circuitry patterns 410 (seeFIGS. 4A-4D).

A rectangular or square shaped laser beam 108 is sized to best match thesubstrate size and the fluence required at the substrate 104 to ablateaway the metal seed layer 402. As the substrate 104 is moved at somepredetermined velocity, a portion of the substrate is exposed to the UVlaser light, for example, at wavelengths of 308 nm or 248 nm.Eventually, all of the substrate 104 will be exposed to the laser beam108; however, as above, only the seed layer 402 reacts when the properfluence is applied.

The size of the laser ablation beam 108 used is affected by severalfactors, including, for example, the size of the substrate 104, thefluence required at the substrate for effective ablation, availablepower, and the like. In any case, as illustrated in FIGS. 5A and 5B, thelaser beam 108 is continuously scanned across the surface 206 of thesubstrate 104 by, for example, moving the substrate 104 and X-Ytranslation stage 102 across the laser beam 108, with the laserapparatus 100 pulsing at a given frequency. In this fashion, the laserbeam 108 is “stepped” across the substrate 104 until the entiresubstrate has been illuminated. Thus, after one corresponding section502 or 504 of the irradiated metal seed layer 402 has been removed, anew section of the substrate 104 that has not been ablated is movedunder the laser beam 108, where the laser apparatus 100 is again pulsedand the metal seed layer 402 in the corresponding irradiated area 502 or504 removed. This “step, pulse, and repeat” process can be implementedat very high rates of speed, typically limited only by the speed oftravel of the stage 102 relative to the laser ablation apparatus 100, oras discussed above, vice-versa.

FIGS. 6A and 6B are photomicrographs, taken at magnifications of ×600and ×500, respectively, of a substrate 104 having a number of metal (Cu)circuit traces 602 formed thereon, and from which the surplus seed layerhas been removed by laser ablation in accordance with an embodiment ofthe present invention. As can be seen in FIGS. 6A and 6B, the laserablation method enables the production of very fine and closely spacedconductive structures 602 with no undercutting and with sharp, distinctedges having no seed layer bridging or shorting between them.

FIGS. 7A and 7B are process flow diagrams respectively illustrating thesequential steps involved in the production of a substrate havingconductive structures formed on a working surface thereof like thoseillustrated in FIGS. 6A and 6B and from which the surplus seed layer hasbeen removed from the substrate surface in accordance with one or moreembodiments of the present invention.

Referring to FIG. 7A, the process begins at S1 with the provision of asubstrate having a either a dielectric or polymer surface or adielectric layer, e.g., a polymer layer, formed thereon. At S2, aconductive seed layer, e.g., Ti/Cu, is formed on the dielectric orpolymer surface or layer, e.g., by sputtering.

At S3, a photoresist is applied to the seed layer, where it is patternedusing conventional photolithography and developing techniques, and atS4, a conductive metal, e.g., Cu, is deposited in the openings of thedeveloped photoresist, e.g., by plating it thereon.

At S5, the photoresist is removed from the substrate, e.g., usingphotoresist stripping techniques, and at S6, the surplus seed layer isablated from the substrate in accordance with the apparatus and methodsdescribed above. As illustrated in FIG. 7B, these include, at S7,placing the substrate on the stage of a laser ablation apparatus 100 ofthe type described above in connection with FIG. 1, and at S8,irradiating an area on the surface of the substrate with a pulse oflaser light from the apparatus having a fluence effective to ablate awaythe surplus seed layer therefrom.

At S9, the seed layer ablated away from the substrate at S8 is capturedusing, e.g., the debris capture system 200 discussed above in connectionwith FIG. 2, and at S10, the stage is moved to an adjacent position andsteps S8 and S9 are repeated in a step-and-repeat fashion until all ofthe surplus seed layer has been removed from the surface of thesubstrate.

In accordance with one or more embodiments, systems and methods areprovided for removing surplus seed layers from substrates using laserablation techniques. The techniques disclosed herein may provide certainadvantages over conventional approaches. For example, a method inaccordance with an embodiment may recoup the surplus seed layer as it islaser irradiated from a substrate (e.g., with a debris removal andcollection system), which under conventional approaches would otherwisebe disposed of or treated as a hazardous waste. As another example, amethod in accordance with an embodiment may eliminate the need topre-clean the substrate prior to removal of the surplus seed layer fromthe surface of a substrate, which may provide an advantage over aconventional approach. In accordance with an embodiment, one or moretechniques disclosed herein may reduce manufacturing costs and cost ofownership (e.g., provide a reduction of wet chemistry, a reduction ofhazardous chemical disposal, a reclamation of surplus seed metals,and/or a high throughput).

As those of skill in this art will by now appreciate, manymodifications, substitutions and variations can be made in and to thematerials, apparatus, configurations and methods of the excess seedlayer removal system in accordance with one or more embodiments of thepresent invention without departing from its spirit and scope.Accordingly, the scope of the present invention should not be limited tothe particular embodiments illustrated and described herein, as they aremerely by way of some examples thereof, but rather, should be fullycommensurate with that of the claims appended hereafter and theirfunctional equivalents.

What is claimed is:
 1. An apparatus comprising: a stage configured toreceive and hold a substrate comprising a surface with patterns formedon a layer; and an irradiating device comprising a projection lens andconfigured to irradiate the surface of the substrate with pulses oflaser light having a selected fluence to remove, from correspondingirradiated areas of the substrate, interstitial portions of the layerbetween the patterns without removing the patterns, wherein the pulsesof laser light are focused through the projection lens, and wherein thestage and the projection lens are configured to move continuouslyrelative each other to irradiate a plurality of areas of the substratewith the pulses of laser light.
 2. A method comprising: receiving andholding a substrate by a stage, wherein the substrate comprises asurface with patterns formed on a layer; irradiating the surface of thesubstrate with pulses of laser light having a selected fluence toremove, from corresponding irradiated areas of the substrate,interstitial portions of the layer between the patterns without removingthe patterns, wherein the pulses of laser light are focused through aprojection lens; and continuously moving the stage and the projectionlens relative to each other to irradiate a plurality of areas of thesubstrate with the pulses of laser light.
 3. The apparatus of claim 1,wherein: the layer comprises a metal seed layer; and the patternscomprise conductive structures formed on the metal seed layer.
 4. Theapparatus of claim 3, wherein the conductive structures comprise traces,bonding pads, conductive bump interconnects, and/or redistribution layer(RDL) traces.
 5. The apparatus of claim 1, wherein: the irradiatingdevice comprises a laser light source operable to produce the pulses oflaser light; and the pulses of laser light produced by the laser lightsource are substantially homogenous in terms of their wavelength, phaseand polarization.
 6. The apparatus of claim 5, wherein the laser lightsource comprises a solid state, an LED or a gas laser.
 7. The apparatusof claim 6, wherein the gas laser comprises an excimer laser.
 8. Theapparatus of claim 7, wherein the excimer laser uses as a gain medium acombination of a noble gas comprising at least one of the groupconsisting of argon, krypton, and xenon, and a reactive gas comprisingat least one of the group consisting of fluorine and chlorine.
 9. Theapparatus of claim 1, wherein the irradiating device further comprisesat least one of the group consisting of: a turning mirror arranged toalter the direction of the pulses of laser light; a shutter operable toselectably block or allow passage of the pulses of laser light; anattenuator operable to selectably attenuate the pulses of laser light;an anamorphic tunnel operable to control the shape of the pulses oflaser light; a homogenizer operable to control the uniformity of thepulses of laser light; an anamorphic condenser lens operable toselectably shape and focus the pulses of laser light; and a maskconfigured to crop the pulses of laser light.
 10. The apparatus of claim1, wherein areas of the surface impinged by the pulses of laser lightare disposed immediately adjacent to or overlap each other.
 11. Theapparatus of claim 1, wherein the selected fluence of the pulses oflaser light is effective to shock, vaporize or ablate the interstitialportion of the layer between the patterns.
 12. The apparatus of claim 1,wherein: the stage is configured to move and the projection lens isfixed; the projection lens is configured to move and the stage is fixed;or the stage and the projection lens are both configured to move. 13.The method of claim 2, wherein: the layer comprises a metal seed layer;and the patterns comprise conductive structures formed on the metal seedlayer.
 14. The method of claim 13, wherein the conductive structurescomprise traces, bonding pads, conductive bump interconnects, and/orredistribution layer (RDL) traces.
 15. The method of claim 13, whereinthe metal seed layer comprises copper (Cu), titanium (Ti),titanium/copper (Ti/Cu), titanium tungsten/copper (TiW/Cu), titanium(Ti), chrome/copper (CrCu), nickel (Ni), and/or palladium (Pd).
 16. Themethod of claim 2, wherein the irradiating and the continuously movingare coordinated to irradiate the entire surface of the substrate in astep, pulse and repeat process.
 17. The method of claim 16, wherein thestep, pulse and repeat process is effected in a straight pass across thesurface of the substrate.
 18. The method of claim 17, wherein the step,pulse and repeat process is effected in a serpentine pass across thesurface of the substrate.
 19. The method of claim 2, wherein theselected fluence of the pulses of laser light is effective to shock,vaporize or ablate the interstitial portion of the layer between thepatterns.
 20. The method of claim 2, wherein the continuously movingcomprises: moving the stage and relative to the projection lens that isfixed; moving the projection lens relative to the stage that is fixed;or moving both the stage and the projection lens.